Ice making apparatus



June 2l, 1960 J. K. NELSON ICE MAKING APPARATUS 3 Sheets-Sheet 1 Filed Feb. 28, 1957 4% "f a v INVENTOR JAMES K. NELsoN BY t ATToRNsv June 21, 1960 J. K. NELSON ICE MAKING APPARATUS Filed Feb. 28, 1957 THERMOSTAT oPr-:Ns

MOLD CONTENTS COOLING TIME 3 Sheets-Sheet 2 REFRIGERATING TEMPERATURE INvNvpR JAMES KNESO ATTORNEY June 21, 1960 J. K. NELSQN 2,941,378

rcs MAKING APPARATUS INVENTOR JAMES K.NELSON SQA@ ATTORNE 2,941,378 Patented June 21,1960- United States Patent Omce ICE MAKmG APPARATUS James K. Nelson, Grove City, house Electric Corporation, poration of Pennsylvania Ohio, assignor to Westing- East Pittsburgh, Pa., a cor- This invention relates to ice making apparatus and more particularly to a control for devices for automatically producing pieces of ice.

This invention constitutes a novel means and method for automatically controlling apparatus adapted to cyclically undergo a series of operations, including the filling of a mold with water to be frozen, the freezing of ice in the mold, and the removal of the frozen contents of the mold. This control is particularly effective in sensing the completion of the ice freezing operation of an ice maker and of thereupon initiating an ice removal operation of the apparatus. Prior to this invention, it has been the practice to initiate the ice removal operation in an automatic ice maker by means of apparatus intended to sense the temperature of the contents of the ice mold; i.e., thermostats or the like have been employed to measure the temperature of the contents of the ice mold, or of some portion of the mold adjacent the con: tents, and to terminate the ice freezing operation and initiate an ice removal operation when a temperature is sensed which is low enough to indicate that the entire contents of the mold are Ibelow 32 degrees F. and consequently in a frozen state. For a number of reasons these prior controls have left much to be; desired so far as their eiciency and reliability of operation. are con. cerned.

The present invention contemplates -a control that is responsive, not to the temperature of the ice mold or its contents, but rather to the temperature of a thermal system analogous to the ice mold and its contents. Physlically, this improved control includes a heat storage 'body or mass thermally disassociated from the ice mold and its contents but subjected to the same .refrigerating effect as is the ice. mold in such a manner that the rate at which heat is removed from this heat storage mass is analogous to the rate at which heat is removed from the contents of the ice mold. The phrase thermally disassociated as herein used denotes a relationship between two elements or components whereby there is substantially no direct transfer or ow of heat from either ofthe elements to the other, so that temperature changes within the thermal system which is composed of the Iice mold and its contents do not directly effect temperature changes within the thermal system of the control.

This control vfurther embodiesthermostatic means for sensing the temperature of the heat storager mass and for controlling, through the medium of an electrical circuit, the various operations performed by the ice making apparatus. Means are also provided in the control for heating the heat storage mass to cause it to undergo a rise in temperature which is analogous to the rise in temperature undergone by the ice mold during the operations wherein ice is removed from the ice mold and replaced wth relatively warm Water prior to commencement of a freezing operation. 'I'he characteristics of this improved control are such that the time required to remove the heat therefrom (heat which has been added bythe heating means), is the same as, or slightly longer than, the time required to remove suicient heat from the ice mold of the ice maker to freeze ice therein.

This invention, then, is a control system utilizing a thermal system analogous to the thermal characteristics of the ice mold andv its contents, wh-ichV thermal system undergoes heating and cooling cycles which are analogous to the heating and cooling cycles to which the ice mold is subjected. Bysensing the temperature of this analogous thermal system, a feat which is physically simpler than sensing the temperature of the contents of the ice mold, a function is readily vobtained that can form the basis 4for controlling.. the operation of the ice making apparatus. The invention also embodies novel features such as an improved wide diiferential .thermostat and novel electrical control circuits for ice makers.

Other novel features, objects and advantages of the invention will appear in the following detailed descriptionV wherein:

Fig. l is a sectional view showing `the interior of the improved control device of this invention;

Fig. 2 vis another sectional view of the control taken along the line II-II of Fig. l;

Fig. 3 is a diagrammatic illustration of the manner in which the improved control of this invention may be applied to an automatic ice maker; j

Figs. 4 and 5 are graphic illustrations of the operation of the control apparatus shown in Figs. 1 to 3;

Figs. 6 and 7` are schematic illustrations of modiied applications for the control apparatus of this invention; and

Fig. 8 is a fragmentary perspective view of the freezing unit of a refrigerator having the ice maker and control of Fig. 3 installed therein. Y

Referring to. the drawings in detail, the numeral 1-1 is employed to indicate the lgroup ofv elements constituting the analogous thermal system of my improved control and which will hereinafter be identified' as the control 11. This control `is adapted to govern the operations of an automatic ice maker of the type illustrated diagrammatically in Fig. 3.

THE ICE MAKING- APPARATUS The ice making `apparatus illustrated in Figs. 3 and ,8 is of the type claimed and described in greater detail in my 'copending application Serial No. 563,490, filed February 6, 1956, and assigned to the assignee of the present invention, and Will be described 4briey herein to iliustrate the functions which must be performed by a control for such apparatus'. v

In this apparatus, an ice mold therein for receiving water to be frozen into ice pieces is refrigerated by suitable means, such as a refrigerantcarrying tube =14 forming a portion of the evaporator or cooling unit of the refrigerated chamber wherein the ice maker is situated. Water is supplied to the mold pockets 13 by illing means comprising an inlet tube 16 con- Inectible to a water measuring and storage chamber 17 by means of a three-way solenoid actuated valve 18, which is capable, when energized,l of connecting the water measuring chamber 17 to a supply pipe 19 containing water under pressure. In the drawing,v the solenoid valve 18 is shown deenergized, in which condition it connects the measuring chamber 17 with the filling` pipe 16 to permit water to flow from the chamber I7 through the pipe 16 into the ice mold pockets 13.

lUpon completion of the ice freezing operation for this apparatus, ie., when the temperature of the contents of the mold pockets 13 has been reduced to the point at which Aall the water therein becomes solidified means must be set irroperation for 'effecting removal of the ice 12 having pockets 13 pieces'f from themold. In the apparatus shown, this ice removing means comprises an electric heater 21 adapted to vaporize iluid contained within the hollow body of the icemold `12A toV increase the pressure `within the mold 12v and distort snap-acting bottom walls 22 of the mold'- pockets `13 to ejectiicetherefrom, all of which is ex-.

plained in'greater detail in my aforementioned applica-V tionSerial No.-v 563,490. Actually, the particular ice ejecting means associated with the mold 12 is illustrative onlygjandthefcontml of. this invention is applicable to numerous knownice-makers employing other means for ejecting icefromia'mold..

f. 'Ijhexcontrol for theicemaking apparatus of Fig.` 3

c must:'.,pi'pvde1for initiation of an ice removing operation bylenerg'izing thezheater 21 afterice has been frozen intheimoldfllprovid'e for termination of the lice removing meansrby 'deener'gzing' the heater 21 when all of theficefpieces have been ejected from the mold 12; and provide: control Vover the water lling means through energization and deenergization of the solenoid valve 18 to refill themoldfwith water'after the ice pieces have been ejectetl,tlaerefron;v In the particular ice making apparatus chosen to illustrate this improved control, no means islrejquredlfot altering the refrigerating effect to which tively, an electric heating element 31 and a thermostat v 32.l The electricheating element 31 functions to add :haatte the heatstorage mass 26 and, therefore, is preferablyembedded within the chamber 29 in a body of electricalginsulang material 33 having good heat con- .dlcts qualities..x- 1

-1'-1`he,tl1ermostat -32sis adapted to sense or measure the temperature of the heat storage mass 26 and is, therefore, preferablygin good heat exchange relation with the mass 26, although itmay, if desired, be electrically insulated therefromgby some means such as the plastic bag indieatedatst.,

The thermostat 32 is of the type commonly referred 'toas a wide dilerential thermostat which simply means that there isasubstantial difference between its cut-on and cut-olf temperatures; the difference between these two temperatures being "the differential of the thermostat. `Whileua number of thermostats of this type are commercially available, the preferred construction of the thermostat. employed this invention-is shown in Figs. 1 and 2in which Aa U-shaped metal frame member 36 surrounds and protects a pair of temperature-responsive bilmetallic;,strips 37 and 38 mounted in cantilever fashion in a`block 39 of insulating material carried between the open 'endslof the frame member 36. The switching means for the thermostat 32 comprises a pair of contacts 41 and 42 carried, respectively, by the frame member 36 and the lower bimetallic strip 38. The upper bimetallic strip 37. is constructed of heavier material than the lower bimetallic strip 38, such that it undergoes a greater deection per degree change in temperature than does the thinner' strip 38, Furthermore, the bimetallic strips 37 and38 are so arranged as to deflect in opposite directions when subjected to the same temperature change. The Larrows in Fig. 2 indicate the direction in which the 'strips 37 and 38 tend to move when they are cooled and their temperature reduced. The upper bimetallic strip 37 carries at the end thereof an insulated slider 43 which transmits motion of the upper strip 37 to the lower strip 38. The upper bimetallic strip 37, by virtue of itsgreater deflection, dominates the lower bimetallic strip 38 in such a manner that, when cooled to a predetermined temperature, the upper bimetallic strip 37 moves the lower bimetallic strip 38 downwardly, closing the contacts 41 and 42.

Ihe lower bimetallic strip 38 is adapted to carry current passing through the circuit established'by the closing of contacts l41 and 42 and is heated thereby. When thus internally heated, the bimetallic strip 38 tends to move downwardly applying an additional closingv force to the contacts y41 and 42,.` Upon the thermostat 32 being thereafter subjected to va rise in temperature, the upper bimetallic strip 37 will move upwardly in a direction to permit the contacts 41 and 42 to open. The additional closing bias applied to the contacts 41 and 42 by the lower bimetallic strip 38 is not, of itself, suicient to maintain the contacts in closed position, but merely delays the-opening of the contacts as the upper bimetallic strip' moves upwardly. It can thus be seen that the thermostat 32 kis adapted to close its contacts 41 and 42 at a predetermined temperature and to open the contacts at another predetermined temperature, higher than the closing temperature. The slider 43, carried on the upper bimetallic strip 37, is movable longitudinally of the strip 37 to vary the effectiveness of the lower bimetallic strip 38 for the purpose of adjusting the differential of the thermostat. The range of the thermostat 32 may be adjusted, that is, its cut-on temperature may be varied, byV means of a set screw 44 carried by the frame mem# ber 36 in a position to adjust the deflection of the upper bimetallic strip 37.

Fig. 3 of the drawings illustrates one manner in which the controll r11 and its components can be electrically connected to the components of an ice maker. Electric current from a source of supply indicated by the lines L1 and L2 is supplied to the control heater 3-1, the ice removing mold heater 21, and the solenoid valve 18 through a parallel circuit under control of the thermostat 32 and a manually actuated line switch 46 which may be employed to deenergize all circuits of theice maker and control. Specifically, current from line L1, after passing through switch 46, is conducted through a lead 47 to one end of the current carrying bimetallic strip 38 in the'thermostat. When contacts 41 and 42 are closed, current flow continues through the thermostat frame member 36 and through one lead 48 to the ice mold heater 21 and the solenoid valve 18, and through another lead 49 to the control heater 3.1. Current is returned from the control heater 31 by means of a lead 41 connected to line L2, and from the mold heater '21 and the solenoid valve 18 by means of a lead 52 also connected to line L2. It will be noted that the connections are such that when the contacts 41 and 42 of control thermostat 32 are closed, the control heater 31, the ice mold heater 21, and the solenoid valve 18 are energized, and when the contacts 41 and 42 are open, all of these components are deenergized.

The control 11 is preferably refrigerated by the same means as is the ice mold d2 and in such a manner that the control 11 and the ice mold 12 are subjected to substantially the same refrigerating effect. When ice making apparatus is applied |to a domestic refrigerator or the like, it is generally situated within the freezingunit or evaporator of the refrigerator wherein it will be sub- -jected to an ambient temperature below the freezing point of water and preferably of the order of 0 F. The freez- -ing unitrincludes a plate 53 which is refrigerated by the refrigerant tubing 14 employed to refrigerate the ice mold :12, as shown in Figs. 3 and 8. The control 11 is placed onvthis refrigerated plate 53, and subjected to substantially the same refrigerating effect as is the ice mold 12. n It will be noted from Figs. 3 and `8 that the control 11 is physically spaced from the ice mold 12, so that there is no transfer of heat between the two. The control 1-1 and ice mold 12 can be said to be thermally disassociated because temperature changes within the mold 12 do not directly affect the temperature of the control, or vice versa. It should be pointed out, however, that the control 11 can function as intendedA although it be in physical contact with the mold1'2, so long as the two are thermally insulated from one another sufficiently to prevent any substantialY iiow of heatfrom either into the other.

Gperatz'on Assume that the cups 13 of the ice meld112- are filled and that the ice pieces therein have.A just become frozen.. Under this circumstance, the control 11,Y that the entire thermalv structureconstituting thecontrol 1'1", will have been cooled to a predetermined temperature at which the contacts 41 and 42 of the.. thermostat 32 are moved to their closed position.. Upon the closing of contacts 41 and 42 an electricalcircuitis established from the supply lines L1 and L2 to energizel the ice mold heater 21, the solenoid valve y18 and the control heater 31. Energization of the mold heater 21 initiates an ice removing operation for the apparatus wherein the ice cup bottom walls 22 are `distorted upwardly to eject the ice pieces from the cups 13, as described in my aforementioned application Serial No. 563,490. Energization of the solenoid valve 18 initiates a water filling operation of the apparatus but does not at this time admit water to the ice mold. Energization of the solenoid valve 18 positionsthe valve passages therein to admit water from the supply pipe 19 into the water measuring and storage chamber 17 wherein the water is held until the valve is again deenergized.

The energization of the control heater 31 enables the heater 31 to add heat to the heat storage mass 26, slowly raising the temperature of the heat storage mass 26 and other components of the control 111. This addition of heat to the control 11 eventually raises the temperature thereof to the point at which the thermostat 32 separates contacts 41 and 42. The hea-ter 31 lis of comparatively low wattage and, in raising the control 11 to the opening temperature of thermostat 32, consumes a period of time that is sucient to permit all of the ice pieces in lthe ice mold 12 to be removed therefrom.

The opening of thermostat contacts 41 and 42 deenergizes the circuit that includes the mold heater 21 and the solenoid valve 1S. Deenergization of the heater 21 terminates the ice removing operation. Deenergization of the solenoid valve 18 connects the water measuring and` storage chamber 17 to the filling pipe 16, conditioning the Water filling means to admit water to the mold pockets 13. The apparatus is thus in condition to cornmencev a freezing oper-ation which begins immediately upon the deenergization of the heater 21 as the refrigerant owing through the tubes 14 removesV heat from the ice mold 12. As the ice mold 12 is being refrigerated, heat is also being removed from the control 11 by the same refrigerating means, in this instance, the refrigerant tubes 14. The rate atwhich heat is removed from the heat storage mass 26 and other components of `the control 11 is governed by the thickness and conductivity of the blanket of insulation 27 surrounding the heat storage mass 26. The thermostat 32 has been adjusted to close contacts 41 and 42 when it senses within the control 11 a predetermined temperature which the control assumes when the ice mold 12 has been refrigerated sufficiently to freeze all of the water therein. This Apredetermined closing temperature of the thermostat 32 need not necessarily be the same temperature as exists in the ice mold 12, although it is preferably below 32 F.

Fig. 4, on sheet 2 of the drawings, illustrates approximate time-temperature relationships forthe mold contents and the control 11 for two cycles of operation (A and B) for the automatic ice' making 'apparatus of Fig. 3.

Fig. 4 illustrates that, while the temperature of the corr trol 11 is not necessarily the same as the temperature of the mold contents, the control system lis so related to the ice freezing apparatus that, upon the control thermo-l stat 32 reaching its closing temperature, the contents of the ice mold have been reduced in temperature. to below 32 F.

The relationship illustrated in Fig. 4 also points out the functioningl of the control 11 under variations in the refrigerating effect to which the ice moldand the con trol are subjected. Cycle Bis shown as extending over a. longer period of .time than cycle A.. In other words,` the refrigeratingeffect to which theice making apparatus is subjected is less in cycler B' than in cycle A, and, con sequently, a longer period off' time is required to freeze the contents of the ice mold. TheI control 11 is, of course subjected to` the. same refrigerating effect as is the ice mold and, consequently; is reduced in temperaf ture to the point at which its thermostat closes at the same point in time that the contents of the mold become frozen or are reduced to slightly below 32 F.

It should be apparent that the control 11 ofv this inA vention, while not directly responsive to temperature conditions existing in the ice mold 12 of the ice maker, nonetheless automatically compensates for variations in the refrigerating effect to which the ice mold 12 is subjected. Suppose, for example, that high ambient temperature conditions in the vicinity of the refrigerator in which the ice making apparatus is located reduce the amount of refrigeration available to the ice mold 12, thereby increasing the time required to freeze ice in the mol'd. The control 11 of this invention would, under such circumst-ances, allow a longer period of time for the freezing operation in the -ice maker or, in other words, automatically delay initiation of Ithe ice removal operation for the ice mold. The control 11 is capable of performing in this manner because it is subjected to the same refrigerating effect as is the ice mold 12 and, consequently, any variations in the refrigerating effect will affect both the ice mold and the control in a like manner. With a reduced refrigerating effect, the rate at which heat is removed from the control heat storage mass 26 is reduced and the control 11 would require refrigeration for a longer period of time in order to reduce its components to the temperature at which the thermostat 32 closes the contacts 41 and 42 to initiate an ice removing cperation. This relationship is further illustrated in Fig. 5 which depicts the effect of changes in the refrigeratingtemperature on the time required to reduce the temperature of the mold contents to 32 and the time required to reduce the control thermostat to its closing temperature.

It is desirable that the thermostat 32 be set to close contacts 41 and 42 at a temperature slightly below that which the control 11 assumes immediately upon completion of the ice freezing operation in the ice mold 12l This lower setting allows additional freezing time to compensate for such variables as slight increases in water inlet temperature which would tend to increase the freezing time of the contents of the mold. Therefore, it will be noted from Fig. 5 that, while the curve depicting time required to cool the control thermostat to its closing temperature closely follows the curve for time required to cool the mold contents to freezing temperature regard'- less of the refrigerating temperature or effect to which these components are subjected, in every instance the control requires a slightly longer period ofv time to reach its closing temperature; providing a margin of safety which assures complete freezing of the mold contents.

By way of illustration, it can be pointed out that for controls constructed in accordance with this invention for` use with ice making apparatus associated with the freezing compartment of a domestic. refrigerator wherein variations in the refrigerating temperature fall4 within the range of 20 F. to +20 F., as illustrated in Fig. '5,

. .5] the optimum operating temperatures for the thermostat 32 of control 11 are: Closing 26 F. and Opening 45 F. In constructing controls in accordance with this invention, it has, therefore, been found desirable to design the thermostat 32 to open'and close approximately at these preselected temperatures. The mass of the heat storage block 26 and the thickness of the insulating jacket 27 are then so chosen as to produce a thermal system which will be cooled from 45 F. to 26 F. in a slightly greater period of time than is required to freeze the contents of the ice mold when the mold and the control are subjected'to the same refrigerating eifect. By-this procedure, the `control 11 is vdesigned to possess a cooling rate which is analogous to the cooling rate of the ice mold and its contents. The actual physical dimensions of the control and yits components are not critical, although, obviously, a proper relationship must be established between the mass of the heat storage block 26 and the insulating value of the jacket 27. As can be well understood by those skilled in the art of refrigeration, the control can employ a.relatively larger heat storage block Z6 if a relatively thinner or less eicient insulating jacket is used, or a relatively smaller heat storage block can be ernployed with a relatively thicker or more efficient insulating jacket.

The output of the heater 31 also -is not a critical factor, as the quantity of heat added to the thermal system of the control is determined bythe cut-off temperature setting of the control thermostat 32. Lowering the wattage of the heater merely increases the period of time required to raise the temperature of the control to cut-off, while raising the wattage of the heater shortens that time. The heater. output should be selected so as to raise the temperature of the control from cut-on to cut-ofi within a period of time that is greater than that required to eject ice from the mold, to insure that the mold will be empty for the next filling operation.

Modifications It should be pointed out that the control method and apparatus described above can be applied to other types of ice making apparatus than that shownin Fig. 3. The control is, for example, readily adaptable to ice makers employing mechanical and/oi motor driven means for eiiecting removal of the ice from the ice mold, such as is described in my copending application Serial No. 566,582, tiled February 20, 1956 and assigned to the assignee of this invention.

The application of the control to ice making apparatus f this type is illustrated schematically in Fig. 6 wherein the control 11, with its thermostat 32 and heater 31, supervises the operation of ice making apparatus, indicated at 65, which is driven by an electric motor 66. In accordance with this invention, the ice making apparatus 65 and the control 1i1 are adapted to be subjected to the same refrigerating eiect and the control 11 is so constructed that the thermostat `32 therein closes when the temperature of the ice making apparatus 65 has been reduced to, or slightly below, freezing. In the electrical circuit for this apparatus, L1 and L2 designate supply lines from a source of electrical current. The line L1 is connected to the thermostat 32 which controls the ow of electrical current to .rst, the control heater 31 which `completes a circuit back to line L2 and, second, the drive motor 66 through a circuit including one pole 67 of a single pole, double-throw switch 68, lead 69 and lead 70, connecting motor 66 to line L2. The switch 68 is actuated by suitable mechanical drive mechanism from the motor 66, as indicated by the dot and dash line 71, and has another pole 72 which receives electrical current through a jumper line 73 connected to supply line L1 ahead of control thermostat 32.

Operation of the Fig. 6 apparatus is as follows: The

--Qdrawing illustrates the position of the electrical switches during an ice freezing operation. Upon the ice becoming Vfrozen and the.- temperature of the control 1'1 being re-` duced to the closing temperature of its thermostat 32, the drive motor 66 is energized to commence an ice ejecting operation within the ice making apparatus 65. Control heater 31 is also energized at this time and raises the temperature of the control 11. Shortly after drive motor 66 is energized by the control 11, the motor, acting through mechanism 71, moves switch 68 from the position shown in Fig. 6 to a position in' which its pole 72 is contacted to establish a by-pass, or holding, circuit for the motor 66 around the control 11. Control 11 eventually reaches the temperature at which its thermostat 32 opens, deenergizing the heater 31. The drive motor 66 continues tov drive the ice making apparatus through the ice ejecting and mold refilling operations. At the end of the iilling operation, the drive motor 36, again acting through mechanism 71, returns switch 68 into contact with its pole 67, conditioning the circuit for a subsequent cooling and freezing operat-ion. Y It will be Anoted that the Fig. 6 embodiment of the invention employs the control 11 to initiate operation of drive motor 66 and that termination of operation of the drive motor 66 is handled by mechanism within the ice making apparatus 65.

It is also within the scope of this invention to employ the control thermostat 32 solely as a means for initiating operation of the drive motor for the ice making apparatus, which, in turn, controls energization of the control heater 3-1. This arrangement is illustrated in Fig. 7. Numeral 65 again designates a schematic showing of ice making apparatus driven by an electric drive motor 66. Energization of the motor 66 from supply lines L1 and Lzis effected by the thermostat 32 of control 11. One side of the thermostat -32 is connected directly to line L1 while the other side is connected to the motor 66 by lead 75. The other side of the drive motor 66 is connected by means of lead 70 to the other supply line L2. The heater 31 for the control 11 is connected between lead and line L2 and is therefore in parallel with the drive motor 66 and is energized when the motor 66 is energized. A by-.pass or jumper circuit around control thermostat 32 is formed by a lead 76 connected to supply line L1, a switch 77 and a lead 78 connected to motor lead 75. The switch 77 is adapted to be actuated between open and closed positions by suitable drive mechanism, indicated as 79, connecting the switch 77 mechanically to the drive motor 66.

The operation of the circuit illustrated in Fig. 7 is as follows: The control 11, upon being cooled to the closing temperature of thermostat 32, energizes the drive motor 66 and the control heater 31. Drive motor 66, acting through drive linkage 79, closes switch 77 establishing a by-pass or holding circuit to the drive motor66 and the control heater 311. Heater 31 raises the temperature of the thermal system of control 11 to the point at which thermostat 32 opens. Drive motor 66, however, continues to run toA drive the ice making mechanism 65 through its ice ejecting and mold refilling operations and thereafter opens switch 77 to deenergize itself and the control heater 31 to condition the apparatus for another freezing operation.

This last described embodiment (Fig. 7) illustrates, then, the manner of employing the drive motor 66 of the automatic ice making apparatusas a timing means for controlling the period 4of energization, not only of itself, but also of the control heater 31.

It also should be apparent that the control 11 of this invention can be effectively employed to supervise and control operation of other Water filling means than the solenoid valve 18-water measuring chamber 17 combination herein described with respect to the Fig. 3 embodiment.

From the foregoing it will be apparent that this invention provides a novel and effective means and method for controlling the operation of an automatic ice maker.

v said mold with water to be frozen, means for refrigerating said mold, means for removing ice from said mold, a heat storage mass thermally disassociatedrfrom the 'contents of said -mold Ibut subjected to the same refrigerating etect as said ice mold, said heat storage mass Abeing constructed and arranged so as to be coolable from a rst predetermined temperature to a second predetermined temperature within a period of time .which corresponds to the period of timev required to freeze all of the water in said ice mold when said mass is subjected to substantially the same refrigerating effect as said ice mold, whereby said heat storage mass has a cooling rate which is analogous to the cooling rate of the contents of said ice mold, a thermostatic element responsive to the temperature of said lheat storage mass, an electric heater for heating said heat storage mass, and switching means actuated by said thermostatic element and having closed and open positions, said switching means when closed completing an electrical circuit including said mass heating means, said ice removing means and said filling means, said thermostatic Vdevice being adapted to move said switching means to closed position when said heat storage mass attains said second predetermined temperature and bein-g adapted to move said switching means to open position when said heat storage mass attains said first predetermined Y temperature.

8. A method of automatically producing pieces Aof ice which comprises filling a mold with water, .sensing the temperature of a heat storage mass which is thermally disassociated from said mold, heating said mass to raise its temperature to a lfirst predetermined value, discontinuing said heating and subjecting said mold and said mass to substantially the same refri-gerating elect, and removing the contents `from said mold responsive to said mass being cooled to a second predetermined temperature.

,9. IA methodof automatically producing pieces of ice which comprises Ifilling a mold with water, heating a heat storage mass which is thermally disassociated'from said mold, discontinuing said heating when the temperature of said mass reaches a predetermined value, sub'- jecting said mold Vand said mass to substantially the same refrigerating elect, and removing the contents from said mold responsive to said mass being cooled to a second predetermined temperature value.

1'10. 11n ice making apparatus adapted for use in a refrigerated compartment of a refrigerator or the like', anice mold adapted to contain water to -be frozen, a heat 4storage mass thenmally disassociated from the contents of said vice mold, said heat storage mass being constructed and arranged so as to he coolable from a first predetermined temperature to a second predetermined temperature a period of time which corresponds to the period of time required to freeze all of the water in said ice mold when said mass is subjected to substantially the same refrigerating elect as said ice mold, whereby said heat storage mass has a cooling rate which is analogous to the cooling rate of the contents of said ice mold, means for removing ice from said mold, means for adding heat to said heat storage mass, and means responsive to the temperature of said heat storage mass -for discontinuing the addition of heat to said mass when the mass reaches said rst predetermined temperature and for initiating operation of said ice removing means when said heat storage mass is cooled to said second predetermined temperature.

References Cited in the file of this patent UNITED STATES PATENTS 

